Conveyer belt



`April 1, 1941. A. BRlLL, l I 2,237,173

cdNvEYEa BELT Filed 0G11. 26. 1939 INVENTOR ATTORNEY Patented Apr. 1, 1941 OFFICE ooNvma BELT Abraham Brill, Youngstown, Ohio, assignor to Lee Rubber and Tire Corporation, Conshohocken, Pa., a corporation of New York i Application October 26, 1939, Serial No. 301,331 Y4 claims. (ci. 19a-19s) 'I'his invention Arelates to conveyer belts. Its chief objects are to provide a conveyer belt adapted to have long life in service and to do this without excessive expense.

More specific objects are to provide a belt adapted to sustain without. quick deterioration the impact of heavy materials, such as coal, ore, crushed stone, or the like, dropped or poured onto the belt, and to do this by providing for eective cushioning of the impact in conjunction with the use of an effective abrasion resisting and cutresisting material for the load-receiving surface layer of the belt.

Such belts ordinarily consist of a belt-body composed of rubberized fabric or cord, a loadreceiving surface layer of highly pigmented, abrasion-resisting rubber, and, between the two, a layer of open-mesh breaker fabric for distributing the force of the material that is to be conveyed as it falls upon the belt.

As the abrasion-resisting surfaceis necessarily of a rather hard composition, it is not very effective as a cushioning element, and the same is true of the fabric-and-rubber or cord-and-rubber belt body, as the layers of reinforcing fabric or cord are separated by only very thin lms of l of a lump of coal, for example, has been transmitted to the belt boch? in a closely localized area instead of being distributed obliquely to the belt body as contemplated in theemployment of the breaker layer.

I attain the above stated objects by providing. in the vicinity of my breaker fabric, and preferablybetween it and the belt body, a layer of relatively soft, low-pigment, cushioning rubber or the like, which is suiciently thick to act eectively as a cushioning element, and to provide proper oblique or lateral distribution of the shook of impact by the breaker layer.

If a thin layer of soft cushioning rubber be laid upon an anvil and hit with a hammer it is likely to be ruptured because of the smallness of the time element involved in the sustaining of live, springy stockv I6, such as lowA pigmented4 the impact. Stated another way, the entire kinetic energy of the falling object has to be absorbed by work done in the distortion' of the belt with the force of impact operating through only a small distance, which means that the force in pounds is relatively great, upon -the principle that the amount o1' work done (energy absorbed ,in work) is equal to the force times the distance through which it acts.

By providing a cushion layer such as to make this distance greater, the maximum force in pounds is correspondingly reduced.

There is a rather definite, critical thickness for a highly effective cushioning layer, depending upon the weight' of the falling particles, the distance through which they fall, andthe modulus of elasticity and the rupture point `of the belt materials used, and ofcourse the sharpness of the particle or the relative area thereof contacting the belt. In large fabric-reinforced rubber belts such as are commonly sold for heavy duty,

for example, Ind that a cushion layer about 5/8" or more in thickness is pronouncedly more eifective in-the usual service than a cushion layer substantially less than M, in thickness, while in belts for lighter service the critical thickness is about 11;".

The cushioning layer can be incorporated in the belt in several forms, some of which are illustrated in the accompanying drawing, of which:

Fig. l is a cross-section of a conveyer belt embodying my invention in its preferred form.

Figs. 2, 3 and 4 are similar sections illustrating other embodiments.

The invention is of especial value in steppedply belts, as illustrated in Fig. 1, in which some of the outer plies of body fabric, like the three outer plies I0, Il and I2 in this gure, terminate, on the load-receiving side of the belt, in longitudinally disposed fabric edges, as at\|3, I3,

quiring to be filled with rubber, or the like.

For lling this space I use a relatively soft,

rubber, and thus obtain the advantages of my invention without greater or substantially greater labor lcost than has been involved in the construction of stepped-ply belts as heretofore made and, while. the cushion stock is a little more expensive than the highly pigmented tread stock l1, the amount of cushion stock required in this embodiment is not very great, because it is restricted to the medial, load-receiving zone of the belt, where it is most needed.

The layer of breaker fabric above referred to is shown at I8, and preferably it is rubberized with a friction coat or coats, and permissibly with a skim coat or coats, of the cushion stock. The advantage of employing the cushion stock as described perhaps can be further elucidated by contemplation of the fact that the cords of the breaker fabric have a substantial amount ,of give and consequently cannot be put under very much tension, so as to perform their function, unless there issuflicient cushion stock between them and the belt body to allow them to be forced out of their normal position, locally, by the impact of the falling object. Y

On the other hand, when there is sufilcient cushion stock, so placed, it yields sufiiciently to Cil permit the breaker fabric to be locally depressed and thus be brought into play as a force distributing and cushioning factor, acting somewhat in the manner of a life-net into which persons safely jump from a vburning building, for example, the life-net, or the breaker fabric, acting with a graduated, increasing, mechanical advantage in stopping the falling object.

Fig. 2 illustrates a similar belt in which only two of,y the outer body plies are stepped, at I8, Il and I9, I9, and cushion stock addition to that required for filling in between the steps is employed, this additional' stock being extended as a layer, 20, 20, upon each of the folded-over margins of the outer ply of body fabric.

In Fig. 3 is shown a belt which is not of the stepped-ply' type but in which a thick layer of cushion stock 2'I is placed between the breaker and the body of the belt.

In Fig. 4 cushion stock 22 is placed between the breaker and the body of the belt and cushion stock 23 is placed between the breaker and the load-receiving stock 24, the'breaker also preferably being rubberized with the cushion stock.

In these andother embodiments the advantages' set forth in the above statement of objects can readily and inexpensively be obtained and other modifications are possible without sacrifice of all of such advantages.

I claim:

1. A conveyer belt comprising a belt body of the steppedhply type and, substantially lling the valley incident to the stepped-ply construction, a cushioning element composed of dense material having substantially the resilient deformability `of vulcanized low-pigment soft rubber, and a relatively hard layer of abrasion resisting material overlying said cushioning element and firmly united therewith.

2. A conveyer belt comprising a belt body ofl .the stepped-ply type and, substantially only the valley incident to the stepped-ply con-l struction, a cushioning element composed of mai terial having substantially the resilient deformability of vulcanized low-pigment soft rubber, and a relatively hard layer of abrasion resisting material overlying said cushioning element and firmly united therewith.

3. A conveyer belt comprising a reinforced belt body, a layer of relatively hard abrasion-resisting material on the load-receiving side of said belt body, and, between the two, a breaker layer and, v

material softer than the wear surface layer and .having sumcient resilient deformability and 

